The 8 Germiest Places in the Mall

Makeup samples

Heading to the makeup counter? A 2005 study found that between 67 and 100% of makeup-counter testers were contaminated with bacteria, including staph, strep, and E. coli. "This study shows us that someone was sick or went to the bathroom, didn’t wash their hands, and then stuck their finger in the sample," Tierno says.

Protect yourself: "Avoid using public makeup samples to apply cosmetics to your lips, eyes, or face," says Tierno, who suggests asking for a single-use unit (you open it, try it, and throw it away). If that’s not available, use a tissue to wipe off the sample and then apply the product to the back of your hand.